Reset Smartthings V2 Outlet UK?

I have the above, believe its Zigbee has a button either side which seems to perform the same task.
I want to know how to hardware reset and then put them into discovery mode. Using with another zigbee router so its just a test.

So, generally with zigbee outlets you hold the button down will plugging in. release the button as soon as you see the light. Then it should be in pairing mode.

Thanks. So if they were in use do they need to be reset or removed from the hub?

unplugging generally resets a zigbee device.